Inhibiting corrosion with chromiumquaternary ammonium salt compositions

Claim 1

THE PROCESS OF PROTECTING METALS AGAINST CORROSION BY CONTACT WITH AQUEOUS LIQUIDS WHICH COMPRISES FEEDING FROM SEPARATE SUPPLY SOURCES INTO AN AQUEOUS INDUSTRIAL PROCESS WATER HAVING A PH WITHIN THE RANGE OF 5.5 TO 8.5, AN AMOUNT OF A WATER SOLUBLE HEXAVALENT COMPOUND OF CHROMIUM CALCULATED AS CRO4 SUFFICIENT TO PROVIDE IN SAID WATER AT LEAST 10 PARTS PER MILLION THEREOF, AND AN AMOUNT OF A WATER DISPERSIBLE QUATERNARY AMMONIUM SALT SUFFICIENT TO PROVIDE FROM 20 TO 60 PARTS PER MILLION THEREOF IN SAID WATER, SAID QUATERNARY AMMONIUM SALT HAVING AT LEAST ONE ACYCLIC ORGANIC RADICAL WITH AT LEAST 8 CARBON ATOMS, CONTACTING THE METALS OF AN AQUEOUS PROCESS SYSTEM WITH SAID WATER SUBSEQUENT TO SAID FEEDING, FOR A PERIOD OF TIME RANGING FROM 7 HOURS TO 30 DAYS SUFFICIENT TO ESTABLISH A PROTECTIVE FILM ON SAID METALS, AND THEN CONTINUING TO TREAT SAID METALS WITH SAID WATER WHILE MAINTAINING FEEDING OF SAID QUATERNARY SALT IN AMOUNTS SUFFICIENT TO MAINTAIN SAID PROTECTIVE FILM.